I feel the legal part is on point. It's also increasingly used by governments to have their cake and eat it too: "We'll completely lock down your devices and run all kinds of analysis on your data, but don't worry, it's all done on-device and all communication is encrypted, so our promise to protect your privacy is kept!"
Kind of a weird concern to be reading on HN, where the sentiment is overwhelmingly that these kinds of systems should be exempt from warrants and discovery.